Cooling of stator by corrugated hose in an electric machine

ABSTRACT

A cooled stator for an electric machine including a rotating rotor wherein the stator comprises an electric sheet metal stack and one or more flexible, deformable cooling channels for guiding the flowing cooling medium in a liquid or gas form, reacting with the stacks. The one or more cooling channels being formed from one or more flexible corrugated hoses made of metal.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a cooled stator for an electric machine with arotating rotor or for an electric linear motor. The stator is in eachcase formed with a magnetic laminated core and comprises one or moreflexibly deformable cooling channels, which act on the laminated core,for flowing cooling medium.

2. Description of the Related Art

DE 197 42 255 C1 discloses a housing-free three-phase machine withparaxial coolant tubes in the stator laminated core. As the coolanttubes are rigid, difficulties may arise when they are inserted in boresin the stator laminated core, in particular when there are bent paths.It is especially necessary to assemble the cooling channels insectionalised and complex fashion from different tube portions withdeflection bends, corner connection bends and similar.

A cooling jacket with a through-flow of liquid for an electric machineis known from the patent publication EP 0 829 946 A1. A tight-fitting,hose-shaped structure, which is flexible and elastic and consists ofrubber or silicone, is proposed as the cooling jacket. This cooling“bag”/hose is not only flexible, but can also be extended considerably.This cooling jacket can therefore sit closely against surfaces of statorlaminated cores of the most varied forms. Since, however, according tothe known proposal, the cooling jacket is extensible and compressible inall directions, it is difficult to introduce this into narrow, paraxialor radial bores of a laminated core. This means that it is alsoproblematic to assemble the cooling device in the stator laminated corein this case.

“DEPANET—Bibliographische Daten” (“Bibliographical data”) discloses abrief abstract of a Chinese patent application CN 1 264 207 according towhich corrugated tubes can be inserted in the cooling device of anelectric motor. However this source reference fails to reveal a moreprecise structure or constructional details on the arrangement of thecorrugated tube.

The object of the invention is to provide a cooled stator which allowsthe cooling device to be rapidly and easily assembled.

BRIEF SUMMARY OF THE INVENTION

In order to solve this object with regard to a stator having thefeatures initially mentioned, the invention proposes that the one or aplurality of cooling channel(s) be formed with one or a plurality offlexible corrugated metal hose. These flexible fluid lines, which areknown per se (cf. “Handbuch der Metallschläuche” (“Metal hosehandbook”), Labhard-Verlag Konstanz 1 999/Witzenmann GmbH, Pforzheim)are distinguished by the fact that they essentially only permitmovements or bends transversely to the longitudinal direction, yetcannot be compressed or accommodate movements in the longitudinaldirection. The use of corrugated tubes or hose of this kind inelectrical machine construction is already known from the Europeanpatent specification EP 0 035 071 B1, although only in connection with awater-cooled rotor, and in this case as a flexible intermediate memberbetween a connecting fitting on the overhang side and a waterdistributing chamber.

The invention makes advantageous use of the axial rigidity of corrugatedhose or tubes when assembling the cooling means in the stator to enablethese to be rapidly inserted in recesses, slots or bores of the statorlaminated core. On account of the flexibility, the corrugated hose canrapidly adapt to the most varied cooling channel paths. The axialrigidity enables them to be easily passed through the cooling bores inthe stator laminated core and inserted. A further advantage which isobtained with the invention lies in the fact that, because the innerwall of the corrugated hose has multiple corrugations, turbulence of thecooling medium flowing therein is increased, which in turn increases theheat exchange and the heat elimination.

According to a special formation of the invention, winding slots whichare provided at the stator laminated core are utilised as guidereceptacles for the corrugated hose. This measure provides the advantageof the corrugated hose or the fluid flowing through them (cooling liquidor air) cooling not just the magnetic or dynamo lamination of thestator, but also the conducting windings or conductors thereof.

On account of their flexibility, the corrugated hose can be guidedaround corners, edges, front sides or similar of the stator andtightened at their ends. This results in an advantageous formation ofthe invention according to which the corrugated hose can be laid in thelaminated core of the stator under tensile stress, which on the one handincreases the mechanical strength and unity of the stator and on theother augments contact between the cooling corrugated hose and thestator parts.

It is expedient to use a corrugated hose of a thermally stable, flexiblematerial which is a good conductor of heat, with small bending radiialso being possible. A corrugated hose consisting of special steelproves to be particularly suitable.

It is expedient to lay the corrugated hose in bores in the laminatedcore which are provided for the cooling channels in order to increasethe heat transfer efficiency between the cooling channel and the statorlaminated core. According to an advantageous formation of the invention,the bores which are required to draw in the corrugated hose may befilled with materials which are good conductors of heat (e.g. aluminium,soldering tin, etc.) in order to further increase thermal conductivity.Zinc, lead or a plastics material may also be used as casting materialson account of their good heat-conductive properties.

Casting with a heat-conductive material is also suitable for corrugatedhose which are laid in winding slots. If, however, direct contactbetween the corrugated hose and the winding is to be avoided, e.g. forreasons of safety and reliability, it is more expedient to lay the hosein the bores. The corrugated hose may also have greater diameters insuch a case. The bores for the corrugated hose may extend axially,paraxially, radially and, in principle, at any conceivable angle to thecentre axis or rotational axis and with any bend corresponding to thesmallest possible bending radius of the corrugated hose.

The use of the stator cooling device according to the invention bothwith electric linear motors and with all known, electric rotary motorsof different designs is possible within the scope of the generalinventive concept. Air, water and all other media which are known forcooling purposes are suitable as cooling medium. The use according tothe invention of the corrugated hose always leads to very good assemblypossibilities and a resulting significant saving of time. The corrugatedhose end of the stator cooling system can be connected to externalcooling fluid circuits and supply devices by means of connectingelements which are known per se, such as plug-in nipples, hose coupling,adapters and the like.

A contributory factor in this respect lies in an advantageous formationof the invention according to which—in the case of electric rotarymotors—the corrugated hose are laid and/or bent in the region of statorfront sides or any end shields which are to be attached such thatmeander-like windings are produced. The curve formation, which is linkedwith this, for the cooling medium flow path promotes the above-mentionedturbulence. In the case of electric linear motors a formation of theinvention in which a plurality of corrugated hose or corrugated hoseportions extending parallel and transversely to the stator longitudinaldirection are connected together by bent portions corresponds to this.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Further details, features, advantages and effects based on the inventionwill emerge from the following description of preferred ways ofimplementing the invention and from the drawings, in which:

FIG. 1 shows a stator according to the invention in longitudinal sectionwith corrugated hose indicated by dot-dash lines as cooling channels,

FIG. 2 is a first front view onto the stator according to FIG. 1,

FIG. 3 is a second, partial front view onto the stator according to FIG.1,

FIG. 4 is a diagrammatic longitudinal view onto the stator of a linearmotor, and

FIG. 5 is a sectional representation according to V—V in FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

The stator which is represented in FIG. 1 is constructed with a magneticlaminated core 1 and is penetrated by paraxial portions 2 (indicated bydot-dash lines) of the cooling channels which are implemented by meansof a corrugated tube 3. In the illustrated example according to FIGS.1-3 a single or one-piece corrugated tube 3 is used to form the coolingchannels. It is of course also possible, without departing from thescope of the invention, for the cooling channels or the cooling channelsystem of the stator to be of multipiece construction with a pluralityof corrugated hose.

According to FIGS. 2 and 3, the corrugated hose is bent over through180° at different entry and exit points 6, 5 at the respective frontsides of the stator, so that corrugated hose deflection bends 4 areproduced at the front sides. The deflection is illustrated by respectiveexit points 5 leading out of the plane of the drawing and entry points 6entering the plane of the drawing. As a result, the corrugated hose 3follows a meandering path which continues in the circumferentialdirection of the stator around the rotational axis 7 and which augmentsthe turbulence of the cooling medium flowing in the corrugated hose 3.

According to FIG. 2, short transverse portions 8 of the corrugated hose3 form the two hose ends and in each case open into a connection screwpart 9 for the feed and discharge of cooling medium.

In FIGS. 4 and 5 an electric linear motor of single-comb construction iscooled by means of two separate corrugated hose 3 a, 3 b. The firstcorrugated hose 3 a is laid directly in the winding slots 10 and extendsvia deflection bends 4 in each case to the next winding slot 10.Similarly to the embodiment according to FIGS. 1-3, the secondcorrugated hose 3 b extends directly in bores 17 of the laminated core1, this taking place in meandering fashion via uniform turns in thedirection of the stator longitudinal axis 11. The meander turns areagain formed by means of a plurality of deflection bends 4, which in theembodiment according to FIGS. 4 and 5 emerge along the statorlongitudinal axis 11 one behind the other in alternating fashion withrespect to the two longitudinal axes of the laminated core 1. The lastexit point 12 is connected via a return bend 13 and a linearlongitudinal portion 14 of the corrugated hose 3 b to a connectionadapter 15, from which the beginning 16 of the corrugated hose alsoextends. The first-mentioned corrugated hose 3 a of the linear motor mayalso be coupled by way of its inlet and outlet end to the connectionadapter 15, in which case the two corrugated hose 3 a, 3 b may beconnected in parallel to the same cooling medium source, for example.

It is expedient—both in the case of the stator for the rotary motoraccording to FIGS. 1-3 and for the electric linear motor according toFIGS. 4 and 5—to fill any interspaces between the corrugated hose 3, 3 alaid in the laminated core 1 and the actual laminated core inside thebore by means of a heat-conductive material.

List of Reference Characters

1 laminated core

2 paraxial portion

3,3 a,3 b corrugated hose

4 deflection bends

5 exit point

6 entry point

7 rotational axis

8 transverse portion

9 connection screw part

10 winding slot

11 longitudinal axis of stator

12 last exit point

13 return bend

14 longitudinal portion

15 connection adapter

16 beginning of corrugated hose

17 bore

What is claimed is:
 1. An improved cooled stator for an electric machinewith a rotating rotor, which stator is formed with a magnetic laminatedcore and comprises at least one flexibly deformable cooling channel,which acts on the laminated core, for flowing cooling medium in a fluidstate, wherein the improvement comprises the cooling channel formed withat least one flexible corrugated metal hose.
 2. An improved cooledstator for an electric linear motor which is formed with a magneticlaminated core and comprises at least one flexibly deformable coolingchannel, which acts on the laminated core, for flowing cooling medium,wherein the improvement comprises the cooling channel formed with atleast one flexible corrugated metal hose.
 3. A stator according to claim1 or 2, wherein winding slots are provided at the stator laminated core,wherein the corrugated hose is in the winding slots and is in contactwith electrically conducting winding parts.
 4. A stator according toclaim 3 wherein the corrugated hose is in the laminated core undertensile stress.
 5. A stator according to claim 3 wherein at least onebore is formed in the laminated core to form the cooling channel,wherein the corrugated hose is in the bore.
 6. A stator according toclaim 3 wherein the corrugated hose is secured to the laminated core bya casting with a heat-conductive material.
 7. A stator according toclaim 6, wherein the casting is a plastics material, selected from thegroup consisting of aluminium, tin, lead, zinc, an alloy with aluminiumand an alloy with zinc.
 8. A stator according to claim 3 wherein atleast a portion of the corrugated hose is parallel to a rotational axis.9. A stator according to claim 8, wherein the corrugated hose is in theregion of stator shields which are attached in order to form windingsextending in meander-like fashion.
 10. A stator according to claim 3wherein a corrugated hose extends parallel and transversely to a statorlongitudinal direction.
 11. A stator according to claim 10, wherein asingle corrugated hose extends in a meander-like path and has transverseportions connected together by bent portions.